Shaft enveloping counterweight apparatus and method

ABSTRACT

Shaft enveloping counterweight ( 10 ) includes an external weight ( 12 ) attached to the outside ( 23 ) hollow shaft ( 22 ). An internal weight plug ( 14 ) is attached to the inside ( 25 ) of hollow shaft ( 22 ) so that hollow shaft ( 22 ) is enveloped by and between the external weight ( 12 ) and the internal weight plug ( 14 ). In a preferred embodiment, a cap ( 16 ) includes a top ( 24 ) and a base ( 26 ) wherein the base ( 26 ) is connected to the internal weight plug ( 14 ) and the top ( 24 ) is connected to the base ( 26 ) and forms and overhanging lip ( 28 ). Base ( 26 ) is also connected to external weight ( 12 ). Further, wrap ( 40 ) covers grip core ( 18 ), external weight ( 12 ), and base ( 26 ).

BACKGROUND OF THE INVENTION

[0001] This invention relates to an improved counterweight for handheld instruments with a shaft. In particular, this invention relates to a shaft enveloping counterweight for golf clubs.

[0002] It is difficult, sometimes extraordinarily so, to swing an instrument with precision. There are several principles of biomechanics, the science of the interaction between muscle fibers, bones, tendons, ligaments, and the various torques and forces exerted on and by them, which are brought into play anytime an instrument with a shaft is manipulated by hand. Two of the most important principles, which relate to the question of the inverse relationship between force and precision and muscular movements, are the size principle and Fitts' law.

[0003] The size principle states that, for any muscular motion, muscle fibers are recruited in order from smallest to largest size. In other words, for a motion requiring very little force, only a few, very small, muscle fibers are used. These small muscle fibers are capable of a great deal of precision, both in amount of force applied and in placement. As the force gets larger, successively larger fibers are “roped in” to participate in the motion. These larger fibers are less and less capable of high precision.

[0004] Fitts' law states, among other things, that the amount of precision that can be attained in any movement decreases exponentially with the velocity of the movement. Essentially, the faster the motion, the less time a person has to make changes, and the greater the effect of small deflections, thus leading to a sharp decrease of precision with increasing velocity.

[0005] In the field of art with which this invention pertains, hand swung instruments with shafts, it has been determined that adding a counterweight to the end of the shaft opposite the working end is beneficial. Through independent testing, Applicant has determined that, when weight is placed above the “pivot point” (i.e. the place the club shaft is gripped by a golfer, for example), it moves the “balance point” closer to the pivot point. At least the following beneficial effects of counterweighting have been determined when used in golf clubs, for example. Counterweights:

[0006] *Decrease the torque and force required in the backswing, allowing greater precision.

[0007] *Decouple the motions of the arm and the club, allowing greater precision.

[0008] *Result in a more favorable placement of the center of percussion, enabling the golfer to more easily hit the “sweet spot”.

[0009] *Increase the inhibition of the tendency of the club to spontaneously rotate along its long axis, similar to the effects of perimeter (heel-toe) weighting.

[0010] The prior art discloses that others have experimented with counterweights as well. Hannon, U.S. Pat. No. 5,632,691, discloses a putter with a weight inserted inside the shaft between the grip and the head. Appledorn, U.S. Pat. No. 5,364,102, discloses a putter with a weight inserted in the grip. Kobayashi, U.S. Pat. No. 5,269,518, discloses a combination weighted head and weighted grip. Benzel, U.S. Pat. No. 5,244,209, discloses an adjustable weight inserted in the shaft at the top of the grip. Reisner, U.S. Pat. No. 4,988,102, discloses a golf club grip with a weighted element in the end and Mitchell, U.S. Pat. No. 4,461,479, discloses another golf club with a weight inserted inside the shaft portion of the grip.

[0011] A drawback to the counterweights known in the art is that they tend to dislodge themselves during use. A further drawback in the art is that the known counterweights are useful only in a limited number of applications. Thus, there is a need in the art for providing an improved counterweight for handheld instruments with shafts. It, therefore, is an object of this invention to provide an improved counterweight for handheld instruments with shafts, with a working end and a grip end, with at least a portion of the grip end including a hollow shaft whereby a counterweight envelopes the hollow shaft from the outside of the hollow shaft and from the inside of the hollow shaft.

SHORT STATEMENT OF THE INVENTION

[0012] Accordingly, the shaft enveloping counterweight of the present invention includes an external weight attached to the outside of a hollow shaft. An internal weight plug is attached inside the hollow shaft so that the hollow shaft is enveloped between the external weight and the internal weight plug. In a preferred embodiment, a cap is connected to the internal weight plug. The cap includes a top and a base wherein the base is connected to the internal weight plug and the top is connected to the base and forms an overhanging lip. In a further embodiment, the base is connected to the external weight. In a still further embodiment, the external weight has a certain length and the internal weight plug extends into the hollow shaft approximately the length of the external weight. In another embodiment, the external weight has a certain length and the internal weight plug extends into the hollow shaft beyond the length of the external weight. In one embodiment, the invention includes a wrap which covers the external weight and the base. In another embodiment, the combined weight of the external weight and the internal weight plug is more than 300 grams. Another embodiment includes a grip core, reduced in length by the cumulative total length of the external weight and the cap, through which the hollow shaft passes. In another embodiment, the grip core is reduced in length so that approximately two inches of shaft protrudes beyond the grip core. And, in yet another embodiment, the handheld instrument with which the shaft enveloping counterweight is utilized is selected from a group including: golf clubs, tennis racquets, badminton racquets, racquetball racquets, lacrosse sticks, and hockey sticks.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Other objects, features and advantages of the present invention will become more fully apparent from the following detailed description of the preferred embodiments, the appended claims and the accompanying drawings in which:

[0014]FIG. 1 is an exploded view of a preferred embodiment of the shaft enveloping counterweight of the present invention including the external weight, the internal weight plug with a cap, and a grip core;

[0015]FIG. 2 is a side view of the invention of FIG. 1 showing a hollow shaft inserted into the grip core and with the external weight attached;

[0016]FIG. 3 is a side view showing the internal weight plug inserted inside the hollow shaft and a cap connected to the internal weight plug; and

[0017]FIG. 4 is a perspective view of the invention with a wrap covering the grip core, the external weight, and the base of the cap.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The preferred embodiments of the present invention are illustrated by way of example in FIGS. 1-4. Referring now to FIG. 1, the shaft enveloping counterweight 10 of the present invention includes external weight 12 and internal weight plug 14. Also shown are cap 16 and grip core 18. A longitudinal hole 20 runs through grip core 18 as well as external weight 12. Longitudinal hole 20 is conformed to exactly receive shaft 22 (not shown, see FIG. 2).

[0019] Cap 16 includes top 24 and base 26. In a preferred embodiment, cap 16 is connected to internal weight plug 14 by means of base 26, and top 24 forms an overhanging lip 28, as will be discussed more fully hereafter.

[0020] Still referring to FIG. 1, it is illustrated that grip core 18, external weight 12 and cap 16, in a preferred embodiment, are formed with a rounded side 30 and a flat side 32. In use with golf clubs, for example, a golfer's fingers wrap around the curved, rounded side 30 of a putter and the thumbs rest on flat side 32. Obviously, any suitable form, for any particular handheld instrument with a shaft, is appropriate.

[0021] Referring now to FIG. 2, shaft 22 is shown. Shaft 22 may be of any known design. That is, shaft 22 may be solid, hollow, made of steel, graphite or any other now known or hereafter developed design. For the purposes of Applicant's invention, all that is important is that shaft 22 include a working end 34 and a grip end 36. Working end 34 is shown attached for use with golf clubs, for example, to putter blade 38. In a preferred embodiment, at least a portion of grip end 36 of shaft 22 is hollow. Further, as previously mentioned, longitudinal hole 20 is conformed to just receive and engage shaft 22, in both the grip core 18 and the external weight 12. As a result, the dimension of longitudinal hole 20, as illustrated in FIG. 2, is reduced by the dimension of the hollow grip end 36 of shaft 22 located therein. It is common, in the golf art, that grip core 18 is a flexible, rubbery, material and grippingly engages the outside 23 of shaft 22. Likewise, longitudinal hole 20 in external weight 12 is conformed to just receive shaft 22 and grippingly engage the outside 23 of shaft 22 as well. Any known adhesives, such as glue, epoxy, or the like may be used to enhance the adherence of the grip core 18 and external weight 12 to the outside 23 of shaft 22.

[0022] Referring now to FIG. 3, internal weight plug 14 is shown inserted, on the inside 25 the hollow grip end 36 of shaft 22. As a result, shaft 22 is completely enveloped, both inside 25 and outside 23 by the combination of external weight 12 and internal weight plug 14. The shaft enveloping counterweight 10, of the present invention, thereby offers superior counterweight attaching functionality. In a preferred embodiment, because internal weight plug 14 is conformed to a size that is just slightly smaller than the inside 25 dimension of hollow grip end 36 of shaft 22, and the external weight 12 is just slightly larger than the outside diversion of the outside 23 of shaft 22, the force fitting insertion of internal weight plug 14 results in an essentially permanent attachment of external weight 12 and internal weight plug 14 to shaft 22. Obviously any now known or hereafter means of attachment may be used such as glue, epoxy, welding and so forth.

[0023] The attachment of external weight 12 and internal weight plug 14 is enhanced by the addition of cap 16. As discussed, base 26 is connected to internal weight plug 14. In a preferred embodiment, base 26 is also connected to external weight 12, by any means known in the art such as epoxy, thereby further securing internal weight plug 14 in place.

[0024] Applicant has also determined that the shaft enveloping counterweight 10 of the present invention is excellent in reducing torsion about the long axis, i.e. shaft, of the club. This reduced torsion is obtained by placing mass anywhere along the shaft 22. That is, it does not specifically require attachment of the mass such as a counterweight as previously described. For example, in another preferred embodiment, internal weight plug 14 is extended beyond external weight 12 and down the inside 25 of shaft 22 covered by grip core 18 to point A. In another embodiment, internal weight plug 14 extends beyond grip core 18 and down the inside 25 of shaft 22 to point B or beyond.

[0025] Referring now to FIG. 4, a preferred embodiment of the invention is illustrated whereby wrap 40 encompasses the outside 23 of shaft 22, grip core 18, external weight 12, and base 26 of cap 16 up to overhanging lip 28. This further secures shaft enveloping counter weight 10 in place. Wrap 40 can be any wrap now known or hereafter developed. In a preferred embodiment, with regard to golf clubs, a standard WINN brand wrap is used.

[0026] With further regard to golf clubs in general, and specifically with regard to putters, the typical putter is 35 inches long. When used with shaft enveloping counterweight 10 of the present invention the putter is designed to be approximately 1.8 to 2 inches longer than normal. The grip core 18 is slightly shorter than typical putters and is placed around the outside 23 of shaft 22 so that grip end 36 of shaft 22 extends approximately 1.8 inches above/beyond the top end of grip core 18. At that point, external weight 12, made of lead or any other suitable heavy material, is placed around the outside 23 of shaft 22 and covers the outside 23 of shaft 22 all the way to the top of shaft 22. Internal weight plug 14 extends 1.8 inches into shaft 22, fits snugly and may be glued in place thereby fully enveloping shaft 22. The preferred total weight of both the external weight 12 and internal weight plug 14 is equal to or greater than 300 grams. Obviously, any desired weight is encompassed by the invention.

[0027] While the shaft enveloping counterweight 10 of the present invention has been disclosed in particular in connection with use with golf clubs, it should be appreciated that external weight 12 in combination with internal weight plug 14 as well as cap 16 provides an improved counterweight attachment means and method for use with a variety of handheld instruments with shafts. While not exclusive, a list of such instruments includes tennis rackets, badminton rackets, racquetball rackets, lacrosse sticks and hockey sticks. Further, handheld tools such as hoes, scythes, and the like are all benefitted by Applicant's shaft enveloping counterweight 10. Further, it should be appreciated by those of ordinary skill in the art that external weight 12 and internal weight plug 14 instead of being two separate pieces may be constructed as a single unitary whole and simultaneously attached to shaft 22. Also, external weight 12 may be of any desired length deemed appropriate.

[0028] While the present invention has been disclosed in connection with a preferred embodiment thereof, it should be understood that there may be other embodiments which fall within the spirit and scope of the invention as defined by the following claims. 

1. In a handheld instrument with a shaft, with a working end and a grip end, with at least a portion of the grip end comprising a hollow shaft, a shaft enveloping counterweight comprising: (a) an external weight attached to the outside of the hollow shaft; and (b) an internal weight plug attached inside said hollow shaft.
 2. The apparatus of claim 1 further comprising a cap connected to the internal weight plug, said cap comprising a top and a base wherein the base is connected to said plug and the top is connected to said base and forms an overhanging lip.
 3. The apparatus of claim 2 wherein said base is connected to said external weight.
 4. The apparatus of claim 1 wherein said external weight has a certain length and the internal weight plug extends into the shaft approximately the length of the external weight.
 5. The apparatus of claim 1 wherein the external weight has a certain length and the internal weight plug extends into the shaft beyond the length of the external weight.
 6. The apparatus of claim 2 further comprising a wrap which covers said external weight and said base.
 7. The apparatus of claim 1 wherein the combined weight of the external weight and the internal weight plug is more than 300 grams.
 8. The apparatus of claim 2 further comprising a grip core, reduced in length by the cumulative total length of said external weight and said cap, through which said shaft passes.
 9. The apparatus of claim 8 wherein the grip core is reduced in length so that approximately 2 inches of shaft protrudes beyond the grip core.
 10. The apparatus of claim 1 wherein the handheld instrument is selected from a group including: golf clubs, tennis racquets, badminton racquets, racquetball racquets, lacrosse sticks and hockey sticks.
 11. In a golf club with a shaft with a bottom connected to a club and a top, with at least part of the top of the shaft hollow, a shaft enveloping counterweight comprising: (a) an external weight attached to the outside of the hollow shaft; (b) an internal weight plug connected to the inside said hollow shaft so that said hollow shaft is enveloped by and between said external weight and said internal weight plug; (c) a grip core through which said hollow shaft passes; and (d) a golf wrap surrounding said grip core and said external weight.
 12. The apparatus of claim 11 further comprising a cap connected to the internal weight plug, said cap comprising a top and a base wherein the base is connected to said internal weight plug and the top is connected to said base and forms an overhanging lip.
 13. The apparatus of claim 12 wherein said base is connected to said external weight.
 14. The apparatus of claim 11 wherein said external weight has a certain length and the internal weight plug extends into the hollow shaft approximately the length of the external weight.
 15. The apparatus of claim 11 wherein said external weight has a certain length and the internal weight plug extends into the hollow shaft beyond the length of the external weight.
 16. The apparatus of claim 12 wherein said golf wrap surrounds said grip core, said external weight, and said base.
 17. The apparatus of claim 11 wherein the combined weight of the external weight and the internal weight plug is more than 300 grams.
 18. The apparatus of claim 11 wherein said grip core is reduced in length so that approximately 1.8 inches of the hollow shaft protrudes beyond said grip core.
 19. In a golf club with a shaft, with a bottom connected to a club and a top, with at least part of the top of the shaft hollow, a method of counterweighting the golf club comprising the steps of: (a) attaching an external weight to the outside of the hollow shaft; and (b) attaching an internal weight plug inside said hollow shaft so that said hollow shaft is enveloped by and between said external weight and said internal weight plug.
 20. The method of claim 19 further comprising the steps of: (a) attaching a grip core to said hollow shaft; (b) connecting a cap to said internal weight plug, said cap constructed with a top and a base, the base connected to said internal weight plug and the top connected to said base and formed with an overhanging lip; and (c) covering said grip core, said external weight and said base with a wrap. 